1. Technical Field
The present invention relates to a technique for efficiently performing search of defected parts in an electro-optical device.
2. Related Art
In an electro-optical device mounted as a display device on a mobile phone or a projector, a liquid crystal panel formed by laminating a TFT (Thin Film Transistor) substrate, a liquid crystal layer, and an opposed substrate is provided. A configuration of such a kind of electro-optical device is as follows. In a display area occupying the center of the TFT substrate, pairs of pixel electrodes and TFTs that are active elements performing switching thereof are arranged in a matrix. Opposed electrodes corresponding to the pixel electrodes are provided on the opposed substrate. In the periphery of the display area of the TFT substrate, an external circuit connection terminal that takes the role of receiving an input of various signals from an external IC, a driving circuit that takes the role of driving the TFTs according to image signals, an inter-substrate connection terminal that takes the role of electrically connecting the TFT substrate and the opposed substrate, and lines that connect them are provided. In the electro-optical device having the configuration described above, when common potential (ground) is given from the IC to the external circuit connection terminal, the potential is applied to the opposed substrate through the inter-substrate connection terminal. In this state, the driving circuit drives the TFT according to the image signal given from the IC to the driving circuit through the external circuit connection terminal. Accordingly, the difference between the potential of the pixel electrode connected to the TFT and the potential of the opposed electrode changes, and the light transmission amounts of the pixels (liquid crystal interposed between the pixel electrode and the opposed electrode) change according to the potential difference. An image that is a group of the pixels is expressed by the change in the light transmission amounts of the pixels. A technique relating to such a kind of electro-optical device is disclosed in JP-A-2007-47746.
In such an electro-optical device, a defect may occur in display due to connection failure of an inter-substrate connection terminal. In this case, it is possible to improve the defect in display by repairing the inter-substrate connection terminal causing the connection failure or replacing it with a new terminal. However, hitherto, in such an electro-optical device, a total of four inter-substrate connection terminals are provided in the four corners of the TFT substrate, respectively, and lines connecting the inter-substrate connection terminals to the external circuit connection terminals in series are additionally provided. For this reason, it is difficult to check whether or not the defect in display is improved by cutting each of the lines forming current paths from the IC connected to the external circuit connection terminal to the inter-substrate connection terminals, and it is difficult to efficiently find the terminal with connection failure from among the four inter-substrate connection terminals.